If sending text message reminders to clients isn't working out for you, you can disable this feature. Here's how:
Click on the three lines in the top left, and choose My Plan from the menu
Across the top, select the "Manage Plan" tab
Toggle the "Client Text Reminders add-on" to "off" (it will appear grey)
Then hit the "Review & Confirm" button in the bottom right
Client text reminders will be disabled and your subscription price will automatically update. You can always come back to your subscription page if you decide you want to give text messaging another shot in the future!